1. Field of the Invention
The present invention relates to a method of processing image data and a system using same. More particularly, it relates to a method and system for reproducing a three dimensional shape of an object from a two dimensional image data of the object, a method and system for extracting features of an object, and a method and system for detecting fingers of human hands used as a man-machine interface media.
2. Description of the Related Art
The most common type of human input interface with a computer system involves some type of transducer or actuator which is manipulated by the user, for example, a CRT keyboard, joystick, track ball, and mouse. All of the prior methods in which these input interface devices are employed, however, suffer from a disadvantage in that they require the user to be in physical contact with the hardware, and that a long learning period is usually required before the user becomes proficient with the handling of such an input device. The prior method also suffer from another disadvantage of a narrow scope within which information can be transmitted, for example, a mouse can only send position and motion vectors to a central processing unit in a computer system.
It is desired to photograph an object by a CCD video camera or other photographic means and to reproduce the three-dimensional shape of the object from that photographed image.
Such a method for reproduction of a three-dimensional shape could be applied, for example, to a visual recognition means in the recognition of the motion of a robot hand and its state of grip in an industrial robot.
Further, as another example of application of the method of reproduction of a three-dimensional shape, there is the application to a recognition means in the case of reproduction of the three-dimensional shape of part of the human body, such as the arm, hand, palm, fingers, etc. in the case of use of that body part as a man-machine interface means in a computer system. The human arm, palm, and fingers, as moving objects, are known to function as a more direct and effective man-machine interface than the man-machine interfaces currently in use in computer systems, for example, indirect man-machine interfaces such as a mouse or joystick. A practical real-time method of reproduction of a three-dimensional shape is desired for a moving object like part of the human body, that is, an object which can change in shape.
In the past, the technique used to reproduce a three-dimensional shape of an object was to detect the vertices and edge portions of the object from the two-dimensional image data taken from an object having a three-dimensional shape and to use this data to reconstruct the shape of the object in a noncontradictory manner in a three-dimensional space.
In these methods for reproduction of three-dimensional shapes, however, when there was insufficient edge or other feature data and the feature data could not be clearly obtained and when mistaken data was mixed in the feature data, there was the problem of difficulty in the reproduction of the three-dimensional shape.
If one wishes to deal with mistaken data in the feature data, it is necessary to consider all the combinations of shapes which could be taken and investigate if they make sense with the input data, so there are cases where the amount of calculation becomes huge when combined. The calculation time becomes extremely long. In use for real time processing for an industrial robot or in use using part of the human body as a man-machine interface, for example, it is not possible to satisfy the requirements for realizing the desired three-dimensional shape in real time.
In particular, the two-dimensional image data obtained by photographing an object having a three-dimensional shape by a video camera or other photographic apparatus does not include depth data, so there is difficulty in reproducing a three-dimensional shape.